Why combine the two jobs
Scaffold is a big part of any roof job, and solar installers also need safe roof access. Doing the roof and the panels as one project often avoids paying for scaffold twice, and the panels are fitted to a roof that is guaranteed to be sound.
Panels should never be fixed to a cement sheet roof that may contain asbestos. Drilling and fixing would disturb the sheets, so the old roof comes off first.
What makes a garage roof suitable
The main points are orientation, pitch, shade and structure. A south-facing or east and west roof slope without tall trees or buildings in the way will generate best. The roof must be strong enough for the rails and panels, and the fixings must suit the new roof covering.
Not every garage is a good candidate, and a decent installer will tell you honestly if yours is not. Photos of the garage, the roof and the neighbouring buildings are the starting point.
Batteries in the garage
A garage is a common place for a home battery and inverter, mounted on a wall away from direct water and vehicle impact. Where the battery goes and how it is protected depends on the product and installer, and the installation must follow the electrical regulations.
Many people connect the garage supply to the house consumer unit at the same time, which is a job for a qualified electrician.
Costs and next steps
Solar and battery systems vary a lot with size and brand. A typical home solar system in the UK is often quoted in the region of £4,000 to £8,000, with a battery adding more. Treat that as a guide, not a quote, and ask for itemised prices.
To start, send photos and say you are interested in solar. The roof is priced first, and the solar part is quoted separately by an installer who works in your area.
Common questions
Can solar panels go on an asbestos roof?
No. Fixings would disturb the sheets. The asbestos roof is taken off and a new roof fitted first.
Will my garage roof be big enough?
A single garage roof fits fewer panels than a house roof, so output is smaller but can still cover a good part of a household's daytime use, especially with a battery.
Do I need planning permission for solar on a garage?
Often not for a roof-mounted system on an existing building, but conditions apply, including to listed buildings and conservation areas. Check with your council.